/*******************************************************************************
 * Copyright (c) 2000, 2011 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Matt Chapman, mpchapman@gmail.com - 89977 Make JDT .java agnostic
 *******************************************************************************/
package org.eclipse.ceylon.ide.eclipse.code.wizard;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceProxy;
import org.eclipse.core.resources.IResourceProxyVisitor;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.core.runtime.OperationCanceledException;
import org.eclipse.core.runtime.Path;
import org.eclipse.core.runtime.Status;
import org.eclipse.jdt.core.IClasspathEntry;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.JavaConventions;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.ToolFactory;
import org.eclipse.jdt.core.compiler.CharOperation;
import org.eclipse.jdt.core.dom.ASTParser;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.PackageDeclaration;
import org.eclipse.jdt.core.util.IClassFileReader;
import org.eclipse.jdt.core.util.ISourceAttribute;
import org.eclipse.jdt.internal.corext.util.Messages;
import org.eclipse.jdt.internal.ui.JavaPlugin;
import org.eclipse.jdt.internal.ui.javaeditor.ASTProvider;
import org.eclipse.jdt.internal.ui.viewsupport.BasicElementLabels;
import org.eclipse.jdt.ui.PreferenceConstants;

public class ClassPathDetector implements IResourceProxyVisitor {

    private HashMap<IPath, List<IPath>> fSourceFolders;
    private List<IResource> fClassFiles;
    private HashSet<IPath> fJARFiles;
    private HashSet<IPath> fCeylonSourceFolders = new HashSet<IPath>();

    private IProject fProject;

    private IPath fResultOutputFolder;
    private IClasspathEntry[] fResultClasspath;

    private IProgressMonitor fMonitor;

    public ClassPathDetector(IProject project, IProgressMonitor monitor) throws CoreException {
        fSourceFolders= new HashMap<IPath, List<IPath>>();
        fJARFiles= new HashSet<IPath>(10);
        fClassFiles= new ArrayList<IResource>(100);
        fProject= project;

        fResultClasspath= null;
        fResultOutputFolder= null;

        if (monitor == null) {
            monitor = new NullProgressMonitor();
        }

        detectClasspath(monitor);
    }


    private boolean isNested(IPath path, Iterator<IPath> iter) {
        while (iter.hasNext()) {
            IPath other= iter.next();
            if (other.isPrefixOf(path)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Function detectClasspath.
     * 
     * @param monitor The progress monitor (not null)
     * @throws CoreException in case of any failure
     */
    private void detectClasspath(IProgressMonitor monitor) throws CoreException {
        try {
            monitor.beginTask("Detecting Ceylon project paths", 4);

            fMonitor= monitor;
            fProject.accept(this, IResource.NONE);
            monitor.worked(1);

            ArrayList<IClasspathEntry> cpEntries= new ArrayList<IClasspathEntry>();

            detectSourceFolders(cpEntries);
            if (monitor.isCanceled()) {
                throw new OperationCanceledException();
            }
            monitor.worked(1);


            IPath outputLocation= detectOutputFolder();
            if (monitor.isCanceled()) {
                throw new OperationCanceledException();
            }
            monitor.worked(1);

            detectLibraries(cpEntries, outputLocation);
            if (monitor.isCanceled()) {
                throw new OperationCanceledException();
            }
            monitor.worked(1);

            if (cpEntries.isEmpty() && fClassFiles.isEmpty()) {
                return;
            }
            IClasspathEntry[] jreEntries= PreferenceConstants.getDefaultJRELibrary();
            for (int i= 0; i < jreEntries.length; i++) {
                cpEntries.add(jreEntries[i]);
            }

            IClasspathEntry[] entries= cpEntries.toArray(new IClasspathEntry[cpEntries.size()]);
            if (!JavaConventions.validateClasspath(JavaCore.create(fProject), entries, outputLocation).isOK()) {
                return;
            }

            fResultClasspath= entries;
            fResultOutputFolder= outputLocation;
        } finally {
            monitor.done();
        }
    }

    private IPath findInSourceFolders(IPath path) {
        Iterator<IPath> iter= fSourceFolders.keySet().iterator();
        while (iter.hasNext()) {
            Object key= iter.next();
            List<IPath> cus= fSourceFolders.get(key);
            if (cus.contains(path)) {
                return (IPath) key;
            }
        }
        return null;
    }

    private IPath detectOutputFolder() throws CoreException {
        HashSet<IPath> classFolders= new HashSet<IPath>();

        for (Iterator<IResource> iter= fClassFiles.iterator(); iter.hasNext();) {
            IFile file= (IFile) iter.next();
            IClassFileReader reader= null;
            InputStream content= null;
            try {
                content= file.getContents();
                reader= ToolFactory.createDefaultClassFileReader(content, IClassFileReader.CLASSFILE_ATTRIBUTES);
            } finally {
                try {
                    if (content != null)
                        content.close();
                } catch (IOException e) {
                    throw new CoreException(new Status(IStatus.ERROR, JavaPlugin.getPluginId(), IStatus.ERROR,
                        Messages.format("error closing file", BasicElementLabels.getPathLabel(file.getFullPath(), false)),
                        e));
                }
            }
            if (reader == null) {
                continue; // problematic class file
            }
            char[] className= reader.getClassName();
            ISourceAttribute sourceAttribute= reader.getSourceFileAttribute();
            if (className != null && sourceAttribute != null && sourceAttribute.getSourceFileName() != null) {
                IPath packPath= file.getParent().getFullPath();
                int idx= CharOperation.lastIndexOf('/', className) + 1;
                IPath relPath= new Path(new String(className, 0, idx));
                IPath cuPath= relPath.append(new String(sourceAttribute.getSourceFileName()));

                IPath resPath= null;
                if (idx == 0) {
                    resPath= packPath;
                } else {
                    IPath folderPath= getFolderPath(packPath, relPath);
                    if (folderPath != null) {
                        resPath= folderPath;
                    }
                }
                if (resPath != null) {
                    IPath path= findInSourceFolders(cuPath);
                    if (path != null) {
                        return resPath;
                    } else {
                        classFolders.add(resPath);
                    }
                }
            }
        }
        IPath projPath= fProject.getFullPath();
        if (fSourceFolders.size() == 1 && classFolders.isEmpty() && fSourceFolders.get(projPath) != null) {
            return projPath;
        } else {
            IPath path= projPath.append(PreferenceConstants.getPreferenceStore().getString(PreferenceConstants.SRCBIN_BINNAME));
            while (classFolders.contains(path)) {
                path= new Path(path.toString() + '1');
            }
            return path;
        }
    }


    private void detectLibraries(ArrayList<IClasspathEntry> cpEntries, IPath outputLocation) {
        ArrayList<IClasspathEntry> res= new ArrayList<IClasspathEntry>();
        Set<IPath> sourceFolderSet= fSourceFolders.keySet();
        for (Iterator<IPath> iter= fJARFiles.iterator(); iter.hasNext();) {
            IPath path= iter.next();
            if (isNested(path, sourceFolderSet.iterator())) {
                continue;
            }
            if (outputLocation != null && outputLocation.isPrefixOf(path)) {
                continue;
            }
            IClasspathEntry entry= JavaCore.newLibraryEntry(path, null, null);
            res.add(entry);
        }
//        Collections.sort(res, new CPSorter());
        cpEntries.addAll(res);
    }


    private void detectSourceFolders(ArrayList<IClasspathEntry> resEntries) {
        ArrayList<IClasspathEntry> res= new ArrayList<IClasspathEntry>();
        Set<IPath> sourceFolderSet= fSourceFolders.keySet();
        for (Iterator<IPath> iter= sourceFolderSet.iterator(); iter.hasNext();) {
            IPath path= iter.next();
            ArrayList<IPath> excluded= new ArrayList<IPath>();
            for (Iterator<IPath> inner= sourceFolderSet.iterator(); inner.hasNext();) {
                IPath other= inner.next();
                if (!path.equals(other) && path.isPrefixOf(other)) {
                    IPath pathToExclude= other.removeFirstSegments(path.segmentCount()).addTrailingSeparator();
                    excluded.add(pathToExclude);
                }
            }
            IPath[] excludedPaths= excluded.toArray(new IPath[excluded.size()]);
            IClasspathEntry entry= JavaCore.newSourceEntry(path, excludedPaths);
            res.add(entry);
        }
        for (IPath p: fCeylonSourceFolders) {
            resEntries.add(JavaCore.newSourceEntry(p));
        }
//        Collections.sort(res, new CPSorter());
        resEntries.addAll(res);
    }

    private void visitCompilationUnit(IFile file) {
        ICompilationUnit cu= JavaCore.createCompilationUnitFrom(file);
        if (cu != null) {
            ASTParser parser= ASTParser.newParser(ASTProvider.SHARED_AST_LEVEL);
            parser.setSource(cu);
            parser.setFocalPosition(0);
            CompilationUnit root= (CompilationUnit)parser.createAST(null);
            PackageDeclaration packDecl= root.getPackage();
            
            IPath packPath= file.getParent().getFullPath();
            String cuName= file.getName();
            if (packDecl == null) {
                addToMap(fSourceFolders, packPath, new Path(cuName));
            } else {
                IPath relPath= new Path(packDecl.getName().getFullyQualifiedName().replace('.', '/'));
                IPath folderPath= getFolderPath(packPath, relPath);
                if (folderPath != null) {
                    addToMap(fSourceFolders, folderPath, relPath.append(cuName));
                }
            }
        }
    }

    private void addToMap(HashMap<IPath, List<IPath>> map, IPath folderPath, IPath relPath) {
        List<IPath> list= map.get(folderPath);
        if (list == null) {
            list= new ArrayList<IPath>(50);
            map.put(folderPath, list);
        }
        list.add(relPath);
    }

    private IPath getFolderPath(IPath packPath, IPath relpath) {
        int remainingSegments= packPath.segmentCount() - relpath.segmentCount();
        if (remainingSegments >= 0) {
            IPath common= packPath.removeFirstSegments(remainingSegments);
            if (common.equals(relpath)) {
                return packPath.uptoSegment(remainingSegments);
            }
        }
        return null;
    }

    private boolean hasExtension(String name, String ext) {
        return name.endsWith(ext) && (ext.length() != name.length());
    }

    /* (non-Javadoc)
     * @see org.eclipse.core.resources.IResourceProxyVisitor#visit(org.eclipse.core.resources.IResourceProxy)
     */
    public boolean visit(IResourceProxy proxy) {
        if (fMonitor.isCanceled()) {
            throw new OperationCanceledException();
        }

        if (proxy.getType() == IResource.FILE) {
            String name= proxy.getName();
            if (hasExtension(name, ".java")) {
                visitCompilationUnit((IFile) proxy.requestResource());
            } else if (hasExtension(name, ".ceylon")) {
                if (proxy.requestFullPath().segmentCount()>2) {
                    fCeylonSourceFolders.add(proxy.requestFullPath().uptoSegment(2));
                }
            } else if (hasExtension(name, ".class")) {
                fClassFiles.add(proxy.requestResource());
            } else if (hasExtension(name, ".jar")) {
                fJARFiles.add(proxy.requestFullPath());
            }
            return false;
        }
        return true;
    }


    public IPath getOutputLocation() {
        return fResultOutputFolder;
    }

    public IClasspathEntry[] getClasspath() {
        if (fResultClasspath == null)
            return new IClasspathEntry[0];
        return fResultClasspath;
    }
}
